Disequilibrium parameter

Of the four possible reactant species, attack by the hydroxyl radical yielded the most nearly constant value of p, but the constancy is unimpressive. It is true that the use of equilibrium partial pressures will be in error, but the disequilibrium parameter (y) of Bulewicz, James, and Sugden (4) depends more on temperature than on composition and should not affect the picture from an isothermal set of flames. 

It is frequently necessary to decide on a mechanism under circumstances which are more complex than that described above, and the use of the disequilibrium parameter may be extended beyond the rather simple case of the hydroxides by an appUcation of ideas advanced in the field of electrochemistry by Pourbaix. ... 

In a system at equilibrium, the electron concentration [E] from an alkali metal at a concentration [X] will fall, in the presence of an acceptor Y, because of the formation of Y ions, and of XY, and the ratio [e]/[eo] will fall from a value 1-0 as [Y] increases along curve A (Fig. 3.24). It is known, however, that the hydrogen atoms are not at equilibrium, and that at any point a disequilibrium parameter y = [H]/[HJ may be defined. 

The environmental conditions for each of the cases considered below are summarized in Table III all these parameters are constant in time. The build up of the nucleation mode of the stable particles and the build up of both the nucleation and accumulation modes of the radon decay products is calculated, and the results are given after a process time of one hour. Figures 1 to 5 show the size distributions of stable and radioactive particles, and Table IV gives the disequilibrium, the equilibrium factor F, the "unattached fraction" f and the plate-out rates for the different daughters. 

The interpretation of Eh-pH diagrams implies assumption of complete equilibrium among the various solutes and condensed forms. Although this assumption is plausible in a compositionally simple system such as that represented in figure 8.20, it cannot safely be extended to more complex natural systems, where the various redox couples are often in apparent disequilibrium. It is therefore necessary to be cautious when dealing with the concept of the system Eh and the various redox parameters. 

Data and interest in disequilibrium in MORB historically started with ( °Th/ U), followed by ( Ra/ °Th) and finally ( Pa/ sy). We follow a similar path in reviewing the general magnitude of disequilibria in MORB (Figure 5). Subsequently we explore finer scale structure and variability of disequilibria with other geochemical and geophysical parameters (Section 3.14.3.5). 

The extent of disequilibrium between the partial pressures of a gas in the surface water and in the atmosphere determines the thermodynamic gradient which drives gas flux. The kinetics of flux ultimately depend on molecular diffusion and larger-scale mixing processes. Molecular diffusivity is generally captured in a dimensionless parameter, the Schmidt number (ratio of viscosity of water to molecular... 

It is reasonable to assume that the disequilibrium is weak, so that both pc and the constant flux j are multiplied by a book-keeping small parameter S when Eq. (97) is used in Eq. (17). The perturbed equation can be expanded in a usual way, and the relation between the flux j and pc is obtained from the solvability condition (81) ... 

These conclusions show that three-body behavior dominates the vibrational energy disposal of the CH X systems, as well as SiH, and GeH. The y values found for the above reactions are model I, (4.7 + 0.7) model II (10 + 1) and model III (15 + 1). Thus, with the aid of surprisal analysis, the product vibrational distributions for all of the above systems can be compactly expressed, within the experimental error, by the parameters X and Xy. The fact that the same vibrational disequilibrium is o%-tained in the above cases confirms, via information theory, that all reactions follow similar dynamics. 

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